Chapter 3 The Basic Structure of a Cell - Weebly
Transcript of Chapter 3 The Basic Structure of a Cell - Weebly
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ORGANS ORGAN SYSTEMS
ORGANISM
Different tissues working together
Different organs working together
More Living Levels
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CELL THEORY
1.Cells are the basic unit of structure and function in an organism (basic unit of life)
2. Plants and animals are made of cells
3. Cells come from the reproduction of existing cells (cell division)
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Number of Cells
Although ALL living things are made of cells, organisms may be:
• Unicellular – composed of one cell
• Multicellular- composed of many cells that may organize into tissues, etc.
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Cell Size and Types
• Cells, the basic units of organisms, can only be observed under microscope
• Three Basic types of cells include:
Animal Cell Plant Cell Bacterial Cell
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Which Cell Type is Larger?
_________ > _____________ > ___________ Plant cell Animal cell Bacteria
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Multicellular Organisms
• Cells in multicellular organisms often specialize (take on different shapes & functions)
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Cell Specialization
• Cells in a multi-cellular organisms become specialized by turning different genes on and off
• This is known as DIFFERENTIATION
Prokaryotes – The first Cells • Cells that lack a nucleus or membrane-
bound organelles
• DNA in a region of the cell (nucleoid region)
• Plasmid – circular chromosome found in some bacteria
• Surrounded by cell memb, cell wall, and sometimes a capsule
• Include bacteria…super simple cells
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Eukaryotes • Cells that HAVE
-a nucleus
-membrane-bound organelles
- larger in size
• Includes protists, fungi, plants, and animals
• More complex type of cells
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Organelles
• Very small (Microscopic)
• Perform various functions for a cell
• Found in the cytoplasm
• May or may not be membrane-bound (surrounded by a membrane)
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Animal Cell Organelles
Nucleolus
Nucleus
Nuclear envelope
Ribosome (attached)
Ribosome (free)
Cell Membrane
Rough
endoplasmic
reticulum
Golgi apparatus
Mitochondrion
Smooth
endoplasmic
reticulum
Centrioles
Plant vs. Animal vs. Bacteria Cells Plant Animal Bacteria
Eukaryotic (nucleus) Has a cell wall made of cellulose Have chloroplasts No centrioles Contain large central vacuole
Eukaryotic(nucleus) No cell wall No chloroplasts Has centrioles for cell division No major vacuole
Prokaryotic (no nucleus) – nucleoid region Has a cell wall made of peptidoglycan No chloroplasts No centrioles No membrane bound organelles No vacuoles
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• Nonliving layer • Found in plants, fungi, &
bacteria • Made of cellulose in
plants • Made of peptidoglycan
in bacteria • Made of chitin in fungi
Cell wall Cell Wall
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Cell or Plasma Membrane
Outside of cell
Inside of cell (cytoplasm)
Cell membrane
Proteins
Protein channel Lipid bilayer
Carbohydrate chains
• Composed of double layer of phospholipids and proteins
• Surrounds outside of ALL cells
• Controls what enters or leaves the cell
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• Lies immediately against the cell wall in plant cells
• Pushes out against the cell wall to maintain cell shape
Cell Membrane in Plants Cell membrane
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• Jelly-like substance enclosed by cell membrane
• Provides a medium for chemical reactions to take place
• Contains organelles to carry out specific jobs
• Found in ALL cells
Cytoplasm of a Cell
cytoplasm
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• Controls the normal activities of the cell b/c…
It contains DNA in the form of chromosomes
The Nucleus
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Nuclear Envelope • Double membrane surrounding
nucleus
• Also called nuclear membrane
• Contains nuclear pores for materials to enter & leave nucleus
• Connected to the rough ER
Nuclear pores
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Inside the Nucleus -
The genetic material (DNA) is found
DNA is spread out And appears as CHROMATIN
in non-dividing cells
DNA is condensed & wrapped around proteins
forming CHROMOSOMES in dividing cells
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What Does DNA do?
DNA is the hereditary material of the cell
• DNA made of many genes • Each gene “codes” for a
specific protein
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Ribosomes
• Made of PROTEINS and ribosomal RNA (rRNA)
• Where protein synthesis occurs (the making of proteins)
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Cytoskeleton
• Helps cell maintain cell shape
• Also help move organelles around
• Made of proteins (microtubules & microfilaments)
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Centrioles
• Found only in animal cells
• Paired structures near nucleus
• Made of bundle of microtubules
• Appear during cell division
• Help to pull chromosome pairs apart to opposite ends of the cell during cell division
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Mitochondrion (plural = mitochondria)
• “Powerhouse” of the cell
• Where cellular respiration occurs (where sugar is broken down to make ATP)
• More active cells like muscle cells have MORE mitochondria
• Both plants & animal cells have mitochondria
• Mitochondria have their own DNA
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MITOCHONDRIA
Surrounded by a DOUBLE membrane
Folded inner membrane called CRISTAE (increases surface area for more chemical reactions) Interior called MATRIX
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Endoplasmic Reticulum - ER
Two kinds of ER ---ROUGH & SMOOTH
• Network of hollow membrane tubules
• Helps with the production of proteins and transports materials through the cell.
• Connects to nuclear envelope & cell membrane
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Rough Endoplasmic Reticulum (Rough ER)
• Proteins are made by ribosomes on ER surface
• They are then threaded into the interior of the Rough ER to be modified and transported
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Smooth Endoplasmic Reticulum
• Smooth ER lacks ribosomes on its surface
• Is attached to the ends of rough ER
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Functions of the Smooth ER
• Carbohydrate metabolism
• Makes membrane lipids (steroids)
• Regulates calcium (muscle cells)
• Destroys toxic substances (Liver)
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Endomembrane System
Includes nuclear membrane connected to ER connected to cell membrane (transport)
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Golgi Bodies • Stacks of flattened sacs
• Have a shipping side and receiving side
• Receive proteins made by ER
• Modify, sort, & package
molecules from ER
for storage within the cell OR
for transport out of cell
Transport vesicle
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Golgi Animation
Materials are transported from Rough ER to Golgi to the cell membrane by VESICLES
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Lysosomes-digesting machines • Contain digestive enzymes.
• Break down food, bacteria, and worn out cell parts for cells
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Lysosome Digestion
• Cells take in food by phagocytosis
• Lysosomes digest the food & get rid of wastes
http://learn.genetics.utah.edu/content/begin/cell
s/insideacell/
Peroxisomes • Similar to lysosomes
• Membrane bound and have enzymes that break down toxic materials in the cell
• By-product of their breakdown is Hydrogen peroxide (H2O2) which they then break down into water and oxygen.
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Cilia & Flagella • Function in moving
cells, in moving fluids, or small particles across the cell surface
• Cilia are shorter and more
numerous on cells
• Flagella are longer and fewer (usually 1-3) on cells
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Vacuoles
• Plant cells have a large central vacuole
• Includes storage of sugars, proteins, minerals, lipids, wastes, salts, water, and enzymes
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Contractile Vacuole
• Found in unicellular protists like paramecia
• Regulate water intake by pumping out excess (homeostasis)
• Keeps the cell from lysing (bursting)
Contractile vacuole animation
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Chloroplasts • Use energy from sunlight to
make own food (glucose) - photosynthesis
• Inner membrane modified into sacs calledThylakoids
• Thylakoids in stacks are called Grana …which are connected
• Stroma – gel like material surrounding thylakoids
Gap Junctions
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• Gap junctions (yellow) are clusters of channels that form tunnels of aqueous connectivity between cells.
• These permit the free passage of ions and small molecules between cells (ex: nerve impulse through heart muscle cells)
Tight Junctions • Tight junctions (blue dots)
between cells are connected areas of the plasma membrane that stitch cells together.
• They prevent the passage of molecules and ions through the space between cells. So materials must actually enter the cells (by diffusion or active transport) in order to pass through the tissue.
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Desmosomes • Desmosomes are even stronger connections that join the
intermediate filaments of neighboring cells.
• Desmosomes are localized patches that hold two cells tightly together. They are common in epithelia (e.g., the skin)
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Bacterial Cells • Bacteria cells have 3 major shapes: coccus (round), bacillus
(rods), and spirilla (coils).
• Bacterial cells can be arranged in different patterns including: strepto (chains), staphylo (clusters), palisades (hinged together), diplo (groups of 2), tetrads (groups of 4), or sarcina (groups of 8, 16 or more).
• Bacteria are classified and named based upon their genetic structure, physical structure, and metabolism
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Bacterial Growth Curve • There are 4 phases in the bacterial growth cycle: lag,
log, stationary, and death.
• Factors that impact microbial growth and survival include: nutrient availability, temperature, pH, moisture, oxygen requirements and light.
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Bacterial Phases • Lag Phase – getting accustomed and starting to eat
food/haven’t started to reproduce
• Log/Exponential phase – taking in nutrients and reproducing
• Stationary phase- no change in number of bacteria - # birth=#death. Bacteria are running out of resources
• Decline/Death phase - accumulation of waste products and depletion of nutrients so bacteria start dying.
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